Subjects: Engineering and technical science >> Biomedical Engineering submitted time 2018-03-15
Abstract： Limited to the system architecture in conventional CT, Artifacts induced by respiratory motion during routine diagnosis severely degrades the image quality. A novel micro-CT system performing well in a quasi-static way is proposed according to the principle of field emission. It employs 35 carbon nanotubes based x-ray tubes and 5 flat detectors, motion artifacts can be greatly suppressed by reducing the gantry rotation times and range under the control of the external sequential when compared with conventional CT system. To validate the feasibility of the proposed system, iterative reconstruction algorithm is adopted on simulation due to sparse sampling .
Peer Review Status:
Awaiting Review
Subjects: Biology >> Neurobiology Subjects: Psychology >> Cognitive Psychology Subjects: Engineering and technical science >> Biomedical Engineering submitted time 2018-03-15
Abstract： Hypnosis is an effective psychological technology in respiratory motion control. In this study, functional magnetic imaging was applied to an intra-subject (n＝13) design hypnosis experiment guided by hypnotists to analyze the respiratory motion control and neural activity in hypnosis. As a result, increased brain activities were observed in visual cortex, sensorimotor cortex, posterior cingulate cortex and middle temporal gyrus, and decreased in dorsolateral prefrontal cortex, cerebellum posterior lobe and supramarginal gyrus. Moreover, compared with normal state, enhanced correlation of brain activities (normal state, r＝0.64; hypnosis state, r＝0.80) was observed within large-scale resting-state networks. Increased connectivity between sensorimotor cortex and visual cortex in hypnosis was also observed, which implies their critical roles in neural mechanisms of hypnosis for respiration control and involvement of cognitive and perceptual processing therein. This study provides new insights for hypnosis study in psychology and cognitive neuroscience.
Peer Review Status:Awaiting Review
Subjects: Engineering and technical science >> Biomedical Engineering submitted time 2018-03-14
Abstract： X-ray shading artifacts lead to CT number inaccuracy, image contrast loss and spatial non-uniformity, and therefore are considered as one of the fundamental limitations of CBCT. In order to solve this problem, a novel shading correction method was proposed. Specifically, we first use multi-threshold segmentation algorithm to segment the original CT image for constructing a template image where each structure is filled with the same CT number of a specific tissue type. Then, the L0 norm smoothing algorithm is used to smooth the CBCT image for constructing an image without texture. By subtracting the template from the image without texture, the residual images from various error sources are low-pass filtered to generate the estimated shading artifacts. Finally, the estimated shading artifacts are added back to the original image for shading correction. Compared with the CT image without correction, the proposed method reduces the overall CT number error from over 113 HU to be less than 13 HU and decreases the non-uniformity from over 9% to be less than 1%. The experimental results demonstrate that the proposed shading correction method using L0 norm smoothing and image segmentation can effectively correct the shading artifacts and its feasibility in clinical application is validated.
Peer Review Status:Awaiting Review
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